Science Starter 10/21REVIEW:

1. How does work increase or decrease kinetic energy?

2. What is work?3. Give an example of work.

4. What affects how much energy and object has?

Notes on Learning Set 2.4

What is potential energy?

Energy that is stored to be transformed/used later

2 Examples:A battery not in use Holding a basketball in the

air

How is elastic potential energy stored?

Elastic energy is stored as potential when you stretch or compress something that wants to snap back to its original form.

2 Examples:When you compress a spring Stretch a rubber band

Like in a wind-up toy

How do you increase the stored elastic potential energy?

For a rubber band you would stretch it further

Which picture has more elastic potential energy?SO for a spring you would compress it more!

How is potential energy stored using gravity?

When you lift the steel ball in Newton’s cradle, you do work. This work is stored as potential energy in the ball. This type of energy is called gravitational potential energy-the energy an

object stores because of its position above the ground.When you release the ball, its gravitational potential is transformed into

kinetic energy.

Which one of the below has more gravitational potential energy?

A cat in a 10 foot Tree

OR

A dog in a high chair

What is a system?

Objects that interact Examples: The engine of a carA mechanical pencil, or A ball and the ground

What is mechanical energy?

The sum of kinetic and potential energy in a system

What is the Law Conservation of mechanical energy?

In a system if there were no friction or air resistance the system’s energy would not leave the system unless an outside force acts upon it.

Is that confusing . . . Lets try to help shall we

Law Conservation of mechanical energy continued . . .

When this ball is falling to the ground it meets air resistance, which it taking some of the ball’s energy because it has to overcome it.

Law Conservation of mechanical energy continued . . .

When the ball hits the ground friction occurs, which takes some of the ball’s energy and transforms it into thermal energy.

Law Conservation of mechanical energy continued . . .

Gravity is an outside force pulling the ball down. Gravity is the outside force acting on the system.

Law Conservation of mechanical energy continued . . .

So to recap . . . If this system did not have air resistance, friction, or any outside forces acting on it then it would not lose any of its energy and never stop bouncing.